The Journal of Pharmacology and Experimental Therapeutics

VERU-111, an orally available tubulin inhibitor, suppresses ovarian tumor growth and metastasis

Ovarian cancer is the most lethal gynecological malignancy, with a 5-year survival rate of approximately 50%. The dismal prognosis is due in part to metastatic disease and acquired drug resistance to conventional chemotherapies such as taxanes. Colchicine binding site inhibitors (CBSIs) are attractive alternatives to taxanes because they could potentially achieve oral bioavailability and overcome drug resistance associated with the prolonged use of taxanes. VERU-111 is one of the most advanced CBSIs that is orally available, potent, and well tolerated and has shown good efficacy in several preclinical solid tumor models. Here, we demonstrate for the first time the in vitro potency of VERU-111 as well as its efficacy at inhibiting tumor growth and metastasis in an orthotopic ovarian cancer mouse model. VERU-111 has nanomolar potency against ovarian cancer cell lines and strongly inhibits colony formation, proliferation, invasion, and migration. VERU-111 disrupts microtubule formation to induce mitotic catastrophe and ultimately apoptosis in a concentration-dependent manner. The efficacy of VERU-111 was comparable with standard chemotherapy paclitaxel, the current first-line treatment of ovarian cancer, with no observed synergy with combination paclitaxel + VERU-111 treatment. In vivo, VERU-111 markedly suppressed ovarian tumor growth and completely suppressed distant organ metastasis. Together, these results support VERU-111 for its potential as a novel therapy for ovarian cancer, particularly for late-stage metastatic disease. SIGNIFICANCE STATEMENT: VERU-111 is an investigational new drug and has comparable efficacy as paclitaxel in suppressing tumor cell proliferation, colony formation, and migration in ovarian cancer models in vitro and has potent in vivo antitumor and antimetastatic activity in an orthotopic ovarian cancer mouse model. VERU-111 has low systemic toxicity and, unlike paclitaxel, is orally bioavailable and is not a substrate for the major drug efflux transporters, making it a promising and attractive alternative to taxane-based therapy.

Oklahoma nitrone-007 is an effective anticancer therapeutic agent targeting inflammatory and immune metabolism pathways in endometrial cancer

Advanced-stage endometrial cancer patients typically receive a combination of platinum and paclitaxel chemotherapy. However, limited treatment options are available for those with recurrent disease, and there is a need to identify alternative treatment options for the advanced setting. Our goal was to evaluate the preclinical efficacy and mechanism of action of the anticancer drug Oklahoma Nitrone-007 (OKN-007) alone and in combination with carboplatin and paclitaxel in endometrial cancer. The effect of OKN-007 on the metabolic viability of endometrial cancer cells in both two- and three-dimensional (2D and 3D) cultures, as well as on clonogenic growth, in vitro was assessed. We also evaluated OKN-007 in vivo using an intraperitoneal xenograft model and targeted gene expression profiling to determine the molecular mechanism and gene expression programs altered by OKN-007. Our results showed that endometrial cancer cells were generally sensitive to OKN-007 in both 2D and 3D cultures. OKN-007 displayed a reduction in 3D spheroid and clonogenic growth. Subsequent targeted gene expression profiling revealed that OKN-007 significantly downregulated the immunosuppressive immunometabolic regulatory enzyme indolamine 2,3-dioxygenase 1 (IDO1) (-11.27-fold change) and modulated upstream inflammatory pathways that regulate IDO1 expression (interferon-gamma [IFN-γ], Janus kinase/signal transducer and activator of transcription [JAK-STAT], transforming growth factor beta [TGF-β], and nuclear factor-kappa B [NF-κB]), downstream IDO1 effector pathways (mammalian target of rapamycin [mTOR] and aryl hydrocarbon receptor [AhR]), and altered T cell signaling pathways. OKN-007 treatment reduced IDO1, sulfatase 2 (SULF2), and TGF-β protein expression in vivo and inhibited TGF-β, NF-κB, and AhR-mediated nuclear signaling in vitro. These findings indicate that OKN-007 surmounts proinflammatory, immunosuppressive, and protumorigenic pathways and is a promising approach for the effective treatment of endometrial cancer. SIGNIFICANCE STATEMENT: Women with advanced and recurrent endometrial cancer have limited therapeutic options. Oklahoma Nitrone-007 (OKN-007), which has minimal toxicity and is currently being evaluated in early-phase clinical trials for the treatment of cancer, is a potential new strategy for the treatment of endometrial cancer.

Deletion of PTP4A3 phosphatase in high-grade serous ovarian cancer cells decreases tumorigenicity and produces marked changes in intracellular signaling pathways and cytokine release

The oncogenic protein tyrosine phosphatase PTP4A3 is frequently overexpressed in human ovarian cancers and is associated with poor patient prognosis. PTP4A3 is thought to regulate multiple oncogenic signaling pathways, including STAT3, SRC, and extracellular signal-regulated kinase. The objective of this study was to generate ovarian cancer cells with genetically depleted PTP4A3, to assess their tumorigenicity, to examine their cellular phenotype, and to uncover changes in their intracellular signaling pathways and cytokine release profiles. Genetic deletion of PTP4A3 using CRISPR/CRISPR-associated protein 9 enabled the generation of individual clones derived from single cells isolated from the polyclonal knockout population. We observed a >90% depletion of PTP4A3 protein levels by western blotting in the clonal cell lines compared with the sham-transfected wild-type population. The wild-type and polyclonal knockout cell lines shared similar monolayer growth rates, whereas the isolated clonal populations 2B4, 3C9, and 3C12 exhibited significantly lower monolayer growth characteristics consistent with their lower PTP4A3 levels. The clonal Ptp4a3 knockout cell lines also had substantially lower in vitro colony formation efficiencies compared with the wild-type cells and were less tumorigenic in vivo. The clonal knockout cells were markedly less responsive to interleukin-6-stimulated migration in a scratch wound assay compared with the wild-type cells. Antibody microarray assays documented differences in cytokine release and intracellular phosphorylation patterns in the Ptp4a3-deleted clones. Bioinformatic network analyses indicated alterations in cellular signaling nodes. These biochemical changes could ultimately form the foundation for pharmacodynamic endpoints useful for emerging anti-PTP4A3 therapeutics. SIGNIFICANCE STATEMENT: Clones of high-grade serous ovarian cancer cells were isolated, in which the oncogenic phosphatase Ptp4a3 gene was deleted using CRISPR/CRISPR-associated protein 9 methodologies. The Ptp4a3-null cells exhibited loss of in vitro proliferation, colony formation, and migration and reduced in vivo tumorigenesis. Marked differences in intracellular protein phosphorylation and cytokine release were seen. The newly developed Ptp4a3 knockout cells should provide useful tools to probe the role of PTP4A3 phosphatase in ovarian cancer cell survival, tumorigenicity, and cell signaling.

Disruption of Ovarian Cancer STAT3 and p38 Signaling with a Small-Molecule Inhibitor of PTP4A3 Phosphatase

Protein tyrosine phosphatase type IVA member 3 (PTP4A3 or PRL-3) is a nonreceptor, oncogenic, dual-specificity phosphatase that is highly expressed in many human tumors, including ovarian cancer, and is associated with a poor patient prognosis. Recent studies suggest that PTP4A3 directly dephosphorylates SHP-2 phosphatase as part of a STAT3-PTP4A3 feedforward loop and directly dephosphorylates p38 kinase. The goal of the current study was to examine the effect of a PTP4A phosphatase inhibitor, 7-imino-2-phenylthieno[3,2-